Surface modified polishing pad

ABSTRACT

In one embodiment, a polishing pad includes a hydrophilic polymer base having a polishing surface, and a metal oxide coating. The metal oxide coating has nanoparticles of metal oxide disposed on the polishing surface. In another embodiment, a processing station includes a rotatable platen, a polishing head, and a precursor delivery system. The polishing head is configured to retain a substrate against the polishing pad. The precursor delivery system is configured to form an oxide coating on a surface of a polishing pad disposed on the platen. In yet another embodiment, a method for modifying a surface of a polishing pad includes wetting the surface of the polishing pad and delivering a precursor to the wetted surface of the polishing pad surface. The method also includes forming a metal oxide coating having nanoparticles of metal oxide on the surface from the precursor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a polishing padhaving a surface modification, and methods of fabricating and using thesame. Additionally, embodiments of the present invention also relate toa chemical mechanical planarization system for use with a surfacemodified polishing pad.

2. Description of the Related Art

In the fabrication of integrated circuits and other electronic deviceson substrates, multiple layers of conductive, semiconductive, anddielectric materials are deposited on or removed from a feature side,i.e., a deposit receiving surface, of a substrate. As layers ofmaterials are sequentially deposited and removed, the feature side ofthe substrate may become non-planar and require planarization and/orpolishing. Planarization and polishing are procedures where previouslydeposited material is removed from the feature side of the substrate toform a generally even, planar or level surface. Chemical mechanicalplanarization (CMP) procedures are useful in removing undesired surfacetopography and surface defects, such as rough surfaces, agglomeratedmaterials, crystal lattice damage, and scratches. The procedures arealso useful in forming features on a substrate by removing excessdeposited material used to fill the features and to provide an even orlevel surface for subsequent deposition and processing. A CMP processgenerally includes pressing a substrate against a polishing surface of apolishing pad in the presence of a polishing media, such as a polishingfluid or slurry. Relative motion is provided between the substrate andpolishing surface to planarize the surface of the substrate in contactwith the pad through one or combination of a chemical, mechanical orelectrochemical process.

During polishing processes, the polishing surface of the pad that is incontact with a feature side of the substrate experiences a deformationand/or wear. The deformation may include smoothing of the polishingsurface or creating an unevenness in the plane of the polishing surface,as well as clogging or blocking pores present on the polishing surface,whereby reducing the ability of the pad to properly and efficientlyplanarized the substrate. Periodic conditioning of the polishing surfaceis required to maintain a consistent roughness, porosity and/orgenerally flat profile across the polishing surface.

One method to condition the polishing surface utilizes an abrasiveconditioning disk that is forced downward against the polishing surfacewhile being rotated and/or swept across at least a portion of thepolishing surface. An abrasive portion of the conditioning disk, whichmay be diamond particles or other hard materials, typically cut into thepad surface, which forms grooves in, and otherwise roughens, thepolishing surface. However, while the rotation and/or downward forceapplied to the conditioning disk may be controlled, the conditioningdisk may not cut into the polishing surface evenly, which creates adifference in roughness across the polishing surface.

Fluid jet systems have alternatively been utilized to condition thepolishing pad in lieu of abrasive disks, but these systems use greatamounts of fluid and are expensive to operate. Other systems utilizingoptical devices (e.g., lasers) that cut into the polishing surface havealso been utilized. However, the optical energy interacts with polishingfluids on the pad, causing boiling of the fluid which may rupture poresin the polishing surface, which is detrimental to uniform conditioning,and may also shorten pad service life.

Therefore, there is a need for an improved polishing pad.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to a polishing padhaving a surface modification, and methods of fabricating and using thesame. In one embodiment, a polishing pad is provided. The polishing padincludes a hydrophilic polymer base having a polishing surface, and ametal oxide coating. The metal oxide coating has nanoparticles of metaloxide disposed on the polishing surface.

In another embodiment, a processing station is provided. The processingstation includes a rotatable platen, a polishing head, and a precursordelivery system. The polishing head is configured to retain a substrateagainst the polishing pad. The precursor delivery system is configuredto form an oxide coating on a surface of a polishing pad disposed on theplaten

In yet another embodiment, a method for modifying a surface of apolishing pad is provided. The method includes wetting the surface ofthe polishing pad and delivering a precursor to the wetted surface ofthe polishing pad surface. The method also includes forming a metaloxide coating having nanoparticles of metal oxide on the surface fromthe precursor.

In yet another embodiment, a method for polishing a substrate on apolishing pad is provided. The method includes providing a polishingfluid to a polishing surface of the polishing pad. The polishing surfacehas a metal oxide coating having nanoparticles of metal oxide disposedon the polishing surface. The method further includes pressing thesubstrate against the polishing surface in the presence of the polishingfluid. The method also includes polishing the substrate against thepolishing surface in the presence of the polishing fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross-sectional view of one embodiment of a polishing pad;

FIG. 2 is a schematic view of a polishing pad disposed in packaging;

FIG. 3 is a top plan view of one embodiment of a processing station; and

FIG. 4 is a partial side view of a precursor delivery device having oneembodiment of a polishing pad disposed below the precursor deliverydevice.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of one embodiment of a polishing pad100. The polishing pad 100 includes a body 102 having a polishingsurface 104. The polishing surface 104 includes a coating 106 thatextends the service life of the polishing pad 100.

The body 102 of the polishing pad 100 may be a polymer based materialsuitable for chemical mechanical polishing a substrate thereon. In oneembodiment, the body 102 is fabricated from a hydrophilic polymer. Thepolymer material may be polyurethane, polycarbonate, a fluoropolymer,polytetrafluoroethylene, polyphenylene sulfide, combinations thereof, orany other suitable hydrophilic polymer. The body 102 may alternativelycomprise open or closed cell foamed polymers, elastomers, felt,impregnated felt, plastics, and other suitable materials compatible withthe processing chemistries.

The polishing surface 104 may include surface features, such as grovesand/or microscopic pore structures (not shown), that assist in materialremoval from a feature side of a substrate that is in contact with thepolishing surface 104 during processing. The surface features may beselected to influence processing attributes, such as polishing mediaretention, polishing or removal activity, and material and fluidtransportation affect the removal rate. In order to facilitate uniformsubstrate to substrate processing results, the polishing surface 104must be periodically conditioned to roughen the polishing surface 104.

The coating 106 provides a nano-abrasive rich layer on the polishingsurface 104. The coating 106 improves the planarization and surfacefinish of the features side of the substrate. The coating 106 may be ametal oxide layer comprised of a plurality of nanoparticles 108. In oneembodiment, the nanoparticles 108 have a diameter size between about 10nm to about 30 nm, for example about 25 nm. In one embodiment, thethickness of the coating 106 may be between about 50 nm to about 500 nm,or 500 Angstroms to about 5,000 Angstroms.

In one embodiment, the coating 106 may be formed by wetting thepolishing surface 104 with water and exposing the wetted surface 104 toa precursor which results in the formation of a layer of metal oxidelayer comprised by nanoparticles 108. The amount of water provided tothe polishing surface 104 may be controlled to ensure that thenanoparticles 108 form on and adhere to the body 102 without formingfree particles of the precursor. In an embodiment wherein the body 102is comprised of polyurethane, water is provided in the form of moistureinherently present in the body 102. The precursor may be selected from amoisture sensitive group of gasses that react with the water wetting onthe hydrophilic polymer body 102. Examples of suitable precursors in gasform may include silane (SiH₄), trimethylaluminum (Al₂(CH₃)₆), germaniumtetrafluoride (GeF₄) or any other suitable moisture sensitive gas whichwill form the coating 106 consisting of nanoparticles 108 made of metaloxide. Nanoparticles 108 formed from the above listed precursors whenexposed to water may be comprised of silicon dioxide (SiO₂), aluminumoxide (Al₂O₃), and germanium dioxide (GeO₂) or other metal oxide. In oneembodiment, the nanoparticles 108 form the coating 106 on the polishingsurface 104 without the use of a binding agent.

In one embodiment, the composition of the nanoparticles 108 may beselected to be nonreactive with the polishing media used in during a CMPprocess. The nanoparticles 108 and polishing media may both comprise thesame metal oxide. For example, a CMP process using an aluminum oxideslurry as the polishing media may utilize a polishing pad 100 havingnanoparticles 108 comprised of aluminum oxide forming the coating 106.For coatings 106 comprised of metal oxide, use of the same metal oxidefor both the polishing media and the nanoparticles 108 advantageouslyprevents the coating 106 from losing its adhesion to the polishingsurface 104 during the CMP process. However, in another embodiment,polishing media which does not contain an abrasive or metal oxide may beused to process the substrate because the nanoparticles 108 willfunction as the abrasive which facilitates material removal from thesubstrate. This advantageously reduces the cost of the polishing media.

FIG. 2 is a schematic view of the polishing pad 100 with coating 106disposed in packaging 200 suitable for transportation and/or storage ofthe polishing pad 100. In one embodiment, the packaging 200 may be apolymer bag or other suitable air-tight container. The packaging 200 maybe vacuum sealed or back-filled with an inert gas 202, such as nitrogenor argon. As such, the coating 106 of the polishing pad 100 may beprotected during shipment and/or storage while in the packaging 200. Thepolishing pad 100 may be removed from the packaging 200 when thepolishing pad 100 is ready for installation and use.

The coating 106 may also be formed on the polishing pad 100 while thepolishing pad 100 is disposed in a substrate processing station. Havinga substrate processing station which is capable of applying the coating106 to the polishing pad 100 allows conventional polishing pads to beconverted into the polishing pad 100 at little expense. Having asubstrate processing station which is capable of applying the coating106 to the polishing pad 100 also allows the coating 106 to be reappliedto the polishing pad 100 in-situ the substrate processing station,thereby extending the service life of the polishing pad 100 and furtherreducing down time associated with changing pads, which advantageouslyreduces the cost of ownership while increasing substrate processingthroughput.

FIG. 3 is a top plan view of the processing station 300 that isconfigured to perform a polishing process, such as a CMP orelectrochemical mechanical planarization (ECMP) process, while alsobeing configured to apply the coating 106 to the processing pad 100. Theprocessing station 300 may be a stand-alone unit or part of a largerprocessing system. Examples of a larger processing system that theprocessing station 300 may be utilized with include REFLEXION®,REFLEXION GT™, REFLEXION LK™, REFLEXION LK ECMP™, and MIRRA MESA®polishing systems, all available from Applied Materials, Inc., locatedin Santa Clara, Calif. It is contemplated that other processing stationsmay be adapted to benefit from the invention, including those from otherequipment manufacturers.

The processing station 300 includes a substrate carrier head 320 (shownin phantom), a platen 330, a slurry delivery arm 306, a conditioningmodule 302, and a precursor delivery device 304. The platen 330, theslurry delivery arm 306, the conditioning module 302, and the precursordelivery device 304 may be mounted to a base 312 of the processingstation 300.

The platen 330 supports the polishing pad 100. The platen 330 is rotatedby a motor (not show) so that the polishing pad 100 is rotated relativeto a substrate 308 retained in the substrate carrier head 320 duringprocessing.

Additionally, water may be provided to the processing station 300 by anynumber of sources. For example, the conditioning module 302, theprecursor delivery device 304 and the slurry deliver arm 306 may allinclude water sources suitable for providing water to the surface of thepolishing pad 100. Alternatively, a stand-alone water source may beutilized to provide water to the processing station 300. In theembodiment depicted in FIG. 3, the conditioning module 302 includes oneor more nozzles 350, coupled to a water source 340, for providing waterto the surface of the polishing pad 100 upstream of the precursordelivery device 304.

The substrate carrier head 320 is configured to retain the substrate 308and controllably urge the substrate 308 against the polishing surface104 of the polishing pad 100 during processing. The substrate carrierhead 320 may also rotate the substrate 308 during processing.

The slurry delivery arm 306 is configured to deliver a polishing media,such as a fluid or slurry, to the polishing pad 100 while the substrate308 is polished on the polishing surface 104. The slurry delivery arm306 may be located in front of or behind the polishing head 320.

The conditioning module 302 is configured to condition the polishing pad100 by removing polishing debris and opening the pores of the polishingpad 100. The conditioning module 302 includes a conditioning disk 310.The conditioning disk 310 may be a brush having bristles made of apolymer material or include an abrasive surface comprising abrasiveparticles. In one embodiment, the conditioning disk 310 may containabrasive particles such as diamonds.

The precursor delivery device 304 is configured to deliver precursorfluid, such as a gas or liquid, to the polishing surface 104 of thepolishing pad 100 where the precursor fluid reacts with the water toform the coating 106. The precursor delivery device 304 includes adelivery head 314 and a delivery arm 316, coupled to a precursor fluidsource 350 by a delivery line 352. In one embodiment, the precursordelivery device 304 may include a heater 402 (shown in FIG. 4) to heatthe precursor fluid as it is deposited on the polishing surface 104. Theheater 402 may be a cartridge heater, a band heater or other suitableheater for heating a fluid.

FIG. 4 is a partial sectional view of the precursor delivery device 304.The delivery head 314 of the precursor delivery device 304 includes oneor more nozzles 400 configured to deliver precursor fluid to thepolishing surface 104 in a closed environment. However, it is alsocontemplated that the nozzle 400 may be configured to spray precursorhaving solid particles to the polishing surface 104. In embodimentswhere the precursor is a gas that may be flammable at room temperature,for example silane, the close proximity of the nozzle 400 to thepolishing surface 104 is beneficial. In one embodiment, the precursordelivery device 304 is in direct contact with the polishing surface 104.

In one embodiment, the one or more nozzles 400 includes a plurality ofnozzles, illustratively shown as nozzles 400 a, 400 b and 400 c. Nozzle404 b is a precursor delivery nozzle coupled to the precursor fluidsource 350 by the delivery line 352 and is configured to deliver aprecursor fluid, such as silane. Nozzles 400 a and 400 c are inert gasnozzles. Nozzles 400 a and 400 c are configured to deliver a curtain ofinert fluid, as nitrogen (N₂) or argon, on either side of the precursordelivery nozzle 404 b to provide an isolated environment for isolatingpotentially flammable gasses from the surrounding environment.

Referring additionally back to FIG. 3, the delivery arm 316 is coupledto the delivery head 314 and attached to the base 312. The delivery arm316 is adapted to provide the nozzle 400 to at least a portion of theradius of the polishing pad 100 in a linear, arcing or sweeping motion.

In operation, a method for polishing of the substrate 308 may begin byproviding the precursor fluid by the precursor delivery device 304 tothe polishing surface 104. Water used in the CMP process, water from themoisture in the polishing pad body 102, or water from a separate sourceis also provided to wet the polishing surface 104. The precursor fluidand the water form and adhere the coating 106 on the polishing surface104. In one embodiment, the polishing pad 100 may be rinsed with wateror deionized water, or any other suitable rinsing fluid to remove excessreactant material and by-products from the coating 106 after forming.The slurry delivery arm 306 then provides polishing media to the coatedpolishing pad 100. The substrate carrier head 320 urges the substrate308 towards the polishing surface 104 to be polished and forms aplanarized surface on the features side of the substrate 308. Theconditioning module 302 then conditions the polishing surface 104 of thepolishing surface 104 as discussed above, or by other suitableconditioning techniques.

The coating 106 may be renewed in-situ, prior to or after polishing thesubstrate 308. Renewing of the coating 106 may occur between processingdifferent substrates on the polishing pad 100. The coating 106 may berenewed on the polishing surface 104 between every substrate polishing,after polishing of a predetermined number of substrates, or as needed.In some embodiments, the polishing surface 104 may be cleaned ofresidual polishing media or other debris using high-pressure water ordeionized water prior to the delivery of the precursor fluid to thepolishing surface 104 and forming the coating 106. As a result, beingable to renew the coating 106 advantageously lengthens the lifetime ofthe polishing pad 100 and reduces costs associated with replacing thepolishing pad 100. Additionally, the in-situ delivery of the coating 106to the polishing surface 104 eliminates the downtime associated withhaving to replace the polishing pad 100.

While the foregoing is directed to embodiments of the invention, otherand further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

What is claimed is:
 1. A polishing pad comprising: a hydrophilic polymerbase having a polishing surface; and a metal oxide coating havingnanoparticles of metal oxide disposed on the polishing surface.
 2. Thepolishing pad of claim 1, wherein the base comprises polyurethane,polycarbonate, a fluoropolymer, polytetrafluoroethylene, orpolyphenylene sulfide.
 3. The polishing pad of claim 1, wherein thenanoparticles of metal oxide comprise silicon dioxide (SiO₂), aluminumoxide (Al₂O₃), or germanium dioxide (GeO₂).
 4. The polishing pad ofclaim 1, wherein the metal oxide coating has a thickness between about50 nm to about 500 nm.
 5. The polishing pad of claim 1, wherein thenanoparticles have a diameter size between about 10 nm to about 30 nm.6. The polishing pad of claim 1, wherein the pad is disposed inpackaging configured for storage of the polishing pad.
 7. A processingstation comprising: a rotatable platen; a polishing head configured toretain a substrate against the polishing pad; and a precursor deliverysystem configured to form an oxide coating on a surface of a polishingpad disposed on the platen.
 8. The processing station of claim 7,wherein the precursor delivery system comprises a precursor deliverynozzle configured to deliver a precursor fluid to the surface of thepolishing pad.
 9. The processing station of claim 8, wherein theprecursor delivery system further comprises a plurality of inert gasnozzles adjacent the precursor delivery nozzle, and configured todeliver a curtain of inert gas.
 10. The processing station of claim 7,wherein the precursor delivery system comprises a heater configured toheat a precursor fluid.
 11. A method for modifying a surface of apolishing pad, comprising: wetting the surface of the polishing pad;delivering a precursor to the wetted surface of the polishing padsurface; and forming a metal oxide coating comprising nanoparticles ofmetal oxide on the surface from the precursor.
 12. The method of claim11, wherein the precursor is a moisture-sensitive gas.
 13. The method ofclaim 12, wherein the precursor gas is silane (SiH₄), trimethylaluminum(Al₂(CH₃)₆), or germanium tetrafluoride (GeF₄).
 14. The method of claim10, wherein the surface of the polishing pad is hydrophilic.
 15. Amethod for polishing a substrate on a polishing pad comprising:providing a polishing fluid to a polishing surface of the polishing pad,the polishing surface having a metal oxide coating having nanoparticlesof metal oxide disposed on the polishing surface; pressing the substrateagainst the polishing surface in the presence of the polishing fluid;and polishing the substrate against the polishing surface in thepresence of the polishing fluid.
 16. The method of claim 15, comprising:forming the metal oxide coating polishing surface in-situ polishing thesubstrate.
 17. The method of claim 15, comprising: forming the metaloxide coating polishing surface prior to polishing the substrate. 18.The method of claim 15, comprising: forming the metal oxide coatingpolishing surface after polishing the substrate.
 19. The method of claim15, comprising wetting the polishing surface of the polishing pad toform the metal oxide coating.
 20. The method of claim 15, wherein thepolishing fluid comprises the metal oxide.